Epson ES-50 Carrier Sheet with part number B12B819471 (or often the similar B12B819451 for the US/global market) is a specialized consumable accessory designed for use with the Epson WorkForce ES-50 and other portable sheet-fed scanners (like the ES-60W, DS-70, DS-80W, etc.).
 
It allows you to safely scan materials that would normally be ruined or cause severe jams in a sheet-fed scanner's rollers.
It acts as a uniform carrier for documents that are not standard rectangular sheets (e.g., magazine clippings, fabric swatches, or cutouts).